Paclitaxel is generally used in cancer chemotherapy regimens to treat tumors. Chemotherapy using paclitaxel is carried out by intravenously injecting paclitaxel at a dosage of 135˜175 mg/m2 into the human body for 3 or more hours once every 3-week period in order to allow paclitaxel to spread throughout the entire body. In this case, paclitaxel is repeatedly administered approximately 4 to 6 times, or possibly more, creating a treatment regime lasting at least 6 months. The in vivo administered paclitaxel reaches affected parts through a complicated physiologic process before showing its medical effects.
Paclitaxel begins to exert medical effects following a gradual increase in its blood concentration which increases in stages throughout the cancer therapy process, so that when the paclitaxel blood concentration continually increases its toxicity becomes evident, and the generation of bone marrow is suppressed, resulting in a reduction in leukocytes and then in increased side effects such as hair loss, peripheral nerve disorder, muscular pain, etc.
Also, it has been reported that since most anti-cancer agents comprising paclitaxel have no effects on resting cells but a mortal one on growing cells, cancer chemotherapy is not effective in treating tumors whose cells divide very slowly, such as prostate cancer. That is to say, in the treatment of tumors whose cells are dividing too slowly, such as prostate cancer, the most serious problem is that not only are cells newly created as a result of cell division apoptotic, but also aged tumor cells do not die.
Presently, a variety of minimally invasive ablation technologies have been studied to treat prostate cancer. For example, radioactive seed implantation using a radioactive isotope includes brachytherapy in the biological tissues, high dose rate brachytherapy, cryoablation, etc.
Radioactive isotope implantation is used to treat tumors by inserting an implant manufactured with Iodine-125 or Palladium-103 into target tissues, but has a problem in that it is impossible to determine a dosage of the isotope suitable for the elimination of cancer. Iridium-192 implants are used in the case of high-dose brachytherapy, but have the restrictive difficulty in removing a radioactive implant from a catheter.
Cryoablation is a therapy including inserting a 6˜8 inch-long tube in the prostate via the rectum and circulating liquid nitrogen through the tube to freeze an affected part. Cryoablation is simple and rarely has complications, but has a problem in that side effects such as urinary obstruction may result following treatment, and thus the catheter should remain inserted in the catheter for a long time. In the U.S.A., about 30% of prostate cancer patients undergo cryoablation, and 27% among them suffer from the symptoms of urinary incontinence. In order to minimize these side effects, tissues around the urethra should be troublesomely warmed to an adequate temperature during the cryotherapy procedure to protect the tissues from damage.